Process for resolving petroleum emulsions



Patented Dec. 24, 1940 rn'ocass Foa aEsoLvING PETROLEUM IEMULSIONS I arating the oil from the water.

Melvin De Groote, University City, Mo., assignor to Petrolite. Corporation, Ltd., Wilmington, Del., a corporation of Delaware No Drawing. Application October 23, 1939, a Serial No. 300,846

Claims.

This invention relates primarily to the treatment of emulsions of mineral oil and water, such as petroleum emulsions for the purpose of sep- One object of my invention is to provide a novel process for resolving petroleunr emulsions of the water-in-oil type, that are commonly re-' ferred to as "cut oil," roily oil, emulsified oil,

etc., and which comprise fine droplets of naturally-occurring waters or brines dispersed in a more or less permanent state throughout the oil which constitutes the continuous phase of the emulsion, my process being particularly adapted to the resolution of crude oil emulsions of the kind obtained in connection with the treatment of flooding of subterranean oil-bearing strata by means of aqueous agents or the like.

Another object of my invention is to provide an economical and rapid process for separating .emulsions which have been prepared under controlled conditions frommineral oils, such as crude petroleum and relatively soft waters or weak brines. Controlled emulsification and sub- I sequent demulsiflcation under the conditions just mentioned is of significant value in removing impurities, particularly salts, from pipe line oil.

Briefly stated, my process consists in subjecting a petroleum emulsion of the water-in-oil type to the action of a treating agent or demulsifying agent of the kind hereinafter described, thereby causing the emulsion to break down and separate into its component parts of oil and water or brine, when the emulsion is permitted to'remain in a quiescent state after treatment, or is subjected to other equivalent separatory procedures.

The treating agent or demulsifying agent contemplated by my process consists of or comprises octadecadiene acid foots which may be employed in the acidic form, or 31 the form of a salt or ester. As is well. known, octadecadiene acid is commonly referred to as 9,11-octadecadiene 1- acid and is usually obtained by subjecting ricinoleic acid to a temperature of approximately 290 to 315 C. The ricinoleic acid employed as a raw material in the manufacture of octadecadiene acid by any of the conventionally employed processes, may be pure ricinoleic acid, or may be ricinoleic acid in admixture with other bodies occurring normally in association therewith, as, for instance, fatty acids obtained from castor oil, and which are commonly known as castor oil fatty acids. Such castor oil fatty acids are conveniently obtained by the splitting of castor oil. Such splitting or saponiflcation process can be conducted in any suitable manner, as, for example, by means of alkalies, the various Twitchells reagents, or by means of a ferment or any suitable method. The technical product known as castor oil fatty acid or acids may contain a certain amount of trlricinolein, diricinolein, and monoricinolein. It is also possible that in the course of a splitting process the heat employed may result in the formation of certain polymolecular compounds obtained by the elimination of water. Thus, in the preparation of octadecadiene acid it is probable, as a general rule, .that the ricinoleic acid or castor oil fatty acid employed does not contain more than approximately 80 to 90 per cent of ricinoleic acid. furthermore, it is sometimes feasible to heat castor oil at a temperature above 200 C., and even as high as that approximating or even above its pyrolytic point, i. e., approximately, 275 to 300 C., and thus obtain an at least partially dehydrated castor 011. Such partially dehydrated castor oil can then be saponi'fied in any of the ways'above indicated, and the resultant acid can then be employed just as eflectively as ricinoleic acid of the kind previously described. For purposes of convenience all these forms of castor oil fatty acid are included in the hereto appended claims within the term ricinoleic acid."

Various methods and procedures are employed in the manufacture of octadecadiene acid from ricinoleic acid of the kind previously described. In all these methods the ricinoleic acid is heated to a temperature above its pyrolytic point, that is, somewhere above 270 to 275 (1., and generally at a temperature not over 290 to 315 C. Having converted the ricinoleic acid by suitable pyrolytic methods in presence or absence of a catalyst into octadecadiene acid by elimination of approximately a molecule of water for each molecule of ricinoleic acid, the subsequent step involves the separation of the octadecadiene acid from the accompanying compounds. As a rule, this is purely a matter of distillation under vacuum and the condensation of the distillate. The temperature of distillation approximates the temperature of pyrolysis, and therefore, in most instances, the operations are conducted simultaneously, that is, the pyrolytic' operation and the distillation are conducted at the same time. As to the manufacture of octadecadiene acid or the like, reference is made to U. S. Patent -No. 2,156,737, dated May 2, 1939, to Priester, and also British Patent No. 306,452, dated May 9, 1930, to Schreiber.

The still residue or foots in such operating pro-. cedure results in a product, which, for want of a better name, is conveniently referred to as octadecadiene acid foots. One can readily convert such octadecadiene acid foots into salts or esters.

For instance, as neutralizing agents one can emhydric alcohols, such as ethyl alcohol, propyl 1 alcohol, octyl alcohol, or polyhydric alcohols,

such as ethylene glycol, glycerol, etc. Furthermore, one can also employ hydroxylated amines, such as monoethanolamine, diethanolamine, triethanolamine, as esterifying agents, that is, in such a manner that they act as alcohols. I

In the hereto appended claims the expression octadecadiene acid foots is used in the generic sense to include all such forms, whether neutralized or not, and whether esterified or not. When it is intended to refer to the octadecadiene acid foots without esteriflcation and without neutralization, such material will be referred to as octadecadiene acid foots in acidic form.

When one compares the analysis of ricinoleic acid which has been subjected to pyrolytic treatment so as to yield a maximum amount of octadecadiene acid, along with the analysis of the octadecadiene acid and octadecadiene acid foots obtained therefrom, and makes allowances for the proportion of the foots to the acid, it becomes perfectly apparent that certain complex changes which are not understood take place when the octadecadiene acid is distilled ofi and the foots remain as a residuum. Depending on the purity of the fatty acids, and conditions of manufacture, the percentage of recovered foots may vary from five to thirty-five percent. As far as is known, no other similar product derived from castor oil has the same composition as that of such octadecadiene foots. This conclusion is based on the examination of the chemical and physical properties of such foots in comparison with similar products. For instance, a typical analysis on the fonts in acidic form is as follows:

Acid value After such acidic material is saponified and split back-by means of hydrochloric acid, as'i's cus- 65 appears available.

15 limitation is included.

tomary in 'the analytical procedures involving fatty material, one obtains an acid value of approximately 200 to 210 and a hydroxyl value of approximately to 60. Numerous other tests, such as reaction to sulfonating agents, etcgsindicate that the material is different from various other fatty derivatives obtainable from ricinoleic acid or castor oil. The foregoing analysis is given by way of illustration only and is not intended to limit the metes and bounds of the composition of the -.octadecadiene acid foots herein contemplated as a demulsifying agent. Insofar that the exact composition of such foots is not known, it appears that the only suitable description is dependent on terms involving the method of manufacture. For this reason, attention is directed to the fact that in the hereto appended claims such procedure is employed for the simple reason that no other suitable method of description In said claims reference to neutralization or esterification, that is, reference to non-acidic forms, is eliminated purely as a matter of convenience and for purposes of brevity. It is understood that such claims which are not limited to the acidic form of the octadecadiene acid foots are intended to include the optional auxiliary step of neutralization or esterification, even though specific reference is not included in said claims, except where an expressed My preferred reagent represents the acidic foots of the kind which corresponds to the above described analysis.

Broadly speaking, then, the manufacture of octadecadiene acid from ricinoleic acid, and more particularly, from castor oil fatty acid, is dependent upon a pyrolytic process which involves a temperature above the conversion point, insofar that the ricinoleic acid is changed or converted into octadecadiene acid. As has been previously indicated, such temperature, that is, the temperature of chemical change or transformation, is indicated as a temperature above the pyrolytic point. Similarly, although 290 to 315 C. is ordinarily the upper range for such reaction, it is possible that in some instances it is desirable to employ a somewhat higher temperature, for instance, possibly 320 to 335 C., or thereabouts. temperature, provided that one does not obtain undue decomposition of the octadecadiene acid, and hence, briefly such higher temperatures may be indicated as being below the point of decomposition. In the hereto appended claims the Word decomposition is intended to refer to the decomposition of octadecadiene acid, and the broadest range of conversion thus can be indicated as-a temperature above the pyrolytic point and below the point of decomposition. It has been pointed out that numerous variables enter into the conditions surrounding the manufacture of octadecadiene acid. They include, among others, the following: The nature of the raw material being converted, the size of the batch; the presence or absence of a catalyst; the rate of heating; the rate of removal in respect to octadecadiene acid; the nature of the container, whether iron or some other metal; the possibility of overheating; whether or not agitation is employed during the process, etc. It is not intended that the process of producing octadecadiene acid shall be limited to any specific set of conditions.

As has been previously pointed out, such octadecadiene acid foots represent an excellent demulsifying agent for oil field emulsions, in view of its relatively low cost. In other words, as far as is known, there is little or no apparent use for such foots, and the price of octadecadiene acid is such as to contemplate the entire cost of the raw material, that is, ricinoleic acid, as well as the expense of .the manufacturing procedures involved. Thus, octadecadiene acid foots are available at a price, in many instances, in the neighborhood of one-half or one-third tlie cost of castor oil or castor oil fatty acids. For this reason, it represents a particularly attractive de mulsifler, notwithstanding the fact that in numerous instances it may not resolve a petroleum emulsion in a greater ratio or more rapidly than some other available demulsifier, but invariably, it is available at only a fraction of the cost of such other more commonly used demulsifier.

The conventional demulsifying agents employed in the treatment of oil field emulsions are commonly used as such, or after dilution with any suitable solvent, such as water, petroleum hydrocarbons, including gasoline, kerosene, stove oil; a coal tar product, such as benzene, toluene, xylene, tar acid oil, cresol, anthracene oil, etc. Alcohols, particularly aliphatic alcohols, such as methyl alcohol, ethyl alcohol, denatured alcohol, propyl alcohol, butyl alcohol, hexyl alcohol, octyl alcohol, may be employed as diluents. Miscellaneous solvents, such as pine oil, carbon tetrachloride, sulfur dioxide extract obtained in the refining of petroleum, etc., may be employed as There is no objection to a higher diluents. Similarly, the material or materials employed as the demulsifying agent of my process may be admixed with one or more of the solvents customarily used in connection with conventional demulsifying agents. Moreover,.said material or materials may be used alone or in admixture with other suitable well known classes of demulsifying agents, such as demulsifying agents of the modified fatty acid type, the petroleum sulfonate type, the alkylated sulfo-aromatic type, etc.

It is known that conventional demulsifying agents may be used in a water-soluble form. or an oil-soluble form, or in a form exhibiting both oil and water solubility. Sometimes they are used in a form which exhibits relatively limited water solubility and relatively limited oil solubility. However, since such reagents are sometimes used in a ratio of 1 to 10,000 or 1 to 20,000, or even 1 to 30,000, such an apparent insolubility in oil and water is not significant, because said reagents undoubtedly have solubility within the concentration employed. The same fact is true in regard to the material or materials employed as the demulsifying agent in my process.

I desire to point out that the superiority of the reagent or demulsifying agent contemplated in my process is based upon its ability to treat certain emulsions at a somewhat lower cost than is possible with other available demulsifiers, or the conventional mixtures thereof. It is believed that the particular demulsifying agent or treating agent herein described will find comparatively limited application, as far as the majority of oil field emulsions are concerned; but I have found that such demulsifying agent has commercial value, as it will economically break or resolve oil field emulsions in a number of cases at a cost which is lower than that possible with the conventional demulsifying agents heretofore available.

In practising my process, a treating agent or demulsifying agent of the kind described above may be brought in contact with the emulsion to be treated in any of the numerous ways now employed in the treatment of petroleum emulsions of the water-in-oil type with chemical demulsifying agents, such, for example, as by introducing the treating agent into the well in which the emulsion is produced; introducing the treating agent into, a conduit through which the emulsion is flowing; introducing the treating agent into a tank in which the emulsion is stored; or introducing the treating agent into a container that holds a sludge obtained from the bottom of an oil storage tank. In some instances, it may be advisable to introduce the treating agent into a producing well in such a way that it will become mixed with water and oil that are emerging from the surrounding strata, before said water and oil enter the barrel of the well pump or the tubing up through which said water and oil flow to the surface of the ground. After treatment, the emulsion is allowed to stand in a quiescent state, usually in a settling tank, and usually at a temperature varying from atmospheric temperature to about 200 F., soas to permit the water or brine to separate from the oil, it being preferable to keep the temperature low enough to prevent the volatilization of valuable constituents of the oil. If desired, the treated emulsion may be acted upon by,one or more of the various kinds of apparatus now used in the operation of breaking petroleum emulsions, such as homogenizers, hay tanks, gun barrels, filters, centrifuges, or electrical dehydrators.

The amount of treating agent that may be required to break the emulsion may vary from approximately onepart of treating agent to 500 parts of emulsion, up to one part of treating agent to 20,000 or even 30,000'parts of emulsion. The proportion depends on the type of emulsion being treated, and also upon the equipmentbeing used, and the temperature employed. In treating exceptionally refractory emulsions of the kinds known as tank bottoms and residual pit oils, the ratio of 1:500, above referred to, may be required. In treating fresh emulsion, i. e., emulsions that will yield readily to the action of chemical demulsifying agents, the ratio of 1230,000, above referred to, may be suflicient to produce highly satisfactory results. In general, I have found that for an average petroleum emulsion a ratio of 1 part of treating agent to 5,000 or 10,000 parts of emulsion will usually be found to produce commercially satisfactory results.

Having thus described my invention, what I claim as new and desire to secure by Letters Patent is:

1. A process for breaking petroleum emulsions of the water-in-oil type, which consists in subjecting the emulsion to the action of a demulsifying agent, comprising octadecadiene acid foots derived by the process of preparing 9,11-octadecadiene l-acid by subjecting ricinoleic acid to a temperature above the pyrolytic point and below 315 0., followed by removal of said octadecadiene acid by vacuum distillation.

2. A process for breaking petroleum emulsions of the water-in-oil type, which consists in subjecting the emulsion to the action of a demulsifying agent, comprising octadecadiene acid foo-ts derived by the process of. preparing 9,11-octadecadiene l-acid by subjecting ricinoleic acid to a temperature above its pyrolytic point and below its decomposition point, followed by removal of said octadecadiene acid by vacuum distillatio'n.

3. A process for breaking petroleum emulsions of the water-in-oil type, which consists in sub jecting the emulsion to the action of a demulsifying agent, comprising octadecadiene acid foots in acidic form, derived by the process of preparing 9,11-octadecadiene l-acid by subjecting ricinoleic acid to a temperature above its pyrolytic point and below 315 0., followed by removal of said octadecadiene acid by vacuum distillation.

4. A process for breaking petroleum emulsions of the water-in-oil type, which consists in subjecting the emulsion to the action of a demulsifying agent, comprising octadecadiene acid foots in acidic form, derived by the process of preparing 9,11-octadecadiene l-acid by subjecting castor oil fatty acid to a temperature above its pyrolytic point and below 315 C., followed by removal of said octadecadiene acid by vacuum distillation.

5. A process for breaking petroleum emulsions of the water-in-oil type, which consists in subjecting the emulsion to the action of a demulsifying agent, comprising octadecadiene acid foots in acidic form, admixed with a suitable solvent; said octadecadiene acid foots being derived by the process of preparing 9,11 octadecadiene 1- acid by subjecting castor oil fatty acid to a temperature above its pyrolytic point and below 315 0., followed by removal of said octadecadiene acid by vacuum distillation.

MELVIN DE GROOTE. 

